1. Field of the Invention
This invention relates to an apparatus and method for change out, i.e. removal and reinstallation, of natural gas meters typically employed in residential and commercial settings without interrupting the gas service to the natural gas consumer.
2. Description of Related Art
State Public Service Commissions require natural gas utilities to exchange residential and commercial meter sets for various reasons every 7-10 years, typically based upon state mandated sampling programs. Some of the reasons for this requirement include leaks reported by the consumer, requirements of corporate policies, exchanges mandated by regulatory bodies, tampering, lot failure programs, and those reported to be reading incorrectly. The current method for exchanging these meters requires a service technician to shut off the flow of gas to the consumer, thereby interrupting the service to the consumer. As part of the exchange, the service technician must enter the premises of the consumer to ensure that all gas appliances are operating properly. At the same time, safety inspections are performed. The total time to complete the exchange at the consumer's premises is approximately 40 minutes, and there is the potential for appliance malfunction requiring the repair of the appliance at the utilities' expense. Not only is this an inconvenience to the consumer whose service is interrupted, but also the interaction with the consumer and the subsequent re-lighting of gas appliances significantly reduces the efficiency of the service technician. Thus, due to consumer inconvenience and the substantial costs to the utilities associated with exchanging meters, it is apparent that a method and apparatus for exchanging a meter without interrupting the flow of gas is highly desirable. In addition, such a method and apparatus would enable concurrent replacement of regulators and service valves, which fail due to corrosion, age, and ice encroachment.
The typical gas meter comprises upward extending, threaded inlet and outlet openings connected by means of inlet and outlet swivels to a meter bar having a gas inlet end and a gas outlet end. The outlet opening is connected with a service line or pipe which runs between the meter outlet and the customer facility. Thus, to change out the meter without interrupting service to the customer requires the maintaining of gas flow through the service line while gas flow through the meter is stopped.
The use of inflatable gas pipeline stoppers or bags for interrupting the flow of gas through a pipeline or service line is well established. Such stoppers are typically employed for temporarily interrupting the flow of gas (or water) through the pipeline or service line while repairs to the pipeline or service line are effected. See, for example, U.S. Pat. No. 1,760,750 to Goodman which teaches a flexible inflatable stopper for gas and water mains that forms a complete closure for the main. In addition, if the stopper buckles or otherwise becomes deformed upon insertion, the placement of the closure will not be prevented. U.S. Pat. No. 1,946,138 to Gardner teaches a pneumatic stopper for a gas pipe including an air bag for stopping the pipe. The device includes a tubular housing and an inflatable bag, interconnected with an air tube which extends within the tubular housing. The air tube and bag may be moved downward with respect to the tubular housing to extend into the pipe after the housing has been threadably attached to the pipe. The air bag may then be inflated to stop flow within the pipe. And, U.S. Pat. No. 3,824,864 to Reigel et al. Teaches a line stopper comprising a housing that is mountable to a conventional pipe tapping machine and a bag insertion assembly mounted in the housing. The insertion assembly includes a slidable insertion tube and an inflatable bag connected at the lower end thereof. The bag includes a rigid neck connected by a knuckle means to the insertion tube to enable the bag to be pivoted into the pipe. The housing is secured to the valve assembly by two pairs of ears which extend outward from the base and which are clamped to the valve assembly by bolts. When the bag is placed in the pipe, the insertion tube covers the edge of the hole in the pipe to prevent abrasion between the bag and the edge of the hole in the pipe. Although each of the prior art devices stops fluid flow within the pipe into which it is inserted, none of the prior art devices provides any means for maintaining flow to a user during the repair process.
It will be appreciated that the direction of the inflatable stopper within the pipe is critical to the success of the repair or other operation being performed. Thus, it is critically important to be able to ensure that the stopper is inserted in the desired direction within the pipe. U.S. Pat. No. 5,439,032 to Petrone teaches an inflatable gas pipeline stopper apparatus including an elongated cylindrical stopper housing for attachment to a gas pipeline using a drilling and tapping machine or air tight clamp assembly and a pair of moveable bag inserting and retracting plunger assemblies including rigid air pipes which are attached to an air source at the upper ends thereof and to the inflatable bags at the bottom ends thereof disposed within the stopper housing. The plunger assemblies are inserted through the stopper housing to extend into the gas pipeline such that one air bag is pointed in an upstream direction within the gas pipeline and the other air bag is directed to a downstream location of the gas pipeline. The bags are indicated to be directional in nature, having a rigid member within the air bag for pointing the air bag in a desired direction. Directional indicators are provided on the moveable bag inserting and retracting plunger assemblies to indicate the direction that the bags are pointed.
Notwithstanding the fact that directional inflatable bags may be designed for insertion in a desired direction, experiments that I have conducted have shown that such bags do not always go into the pipe in the indicated direction. Accordingly, there is a need for a flexible inflatable bag insertion apparatus which precludes insertion of the bags into the pipe in the wrong direction.